In my recent post on Plants and Air Pollution, I have given a general idea about how plants are also affected by air pollution as we humans. For some, it might be a new concept but for environmentalists its a well known fact. I am here to provide you all with a more detailed idea about effects of air pollution on plants so that you might understand how plants are harmed by air pollution.
Air pollution, a worldwide concern, we have been reading about it since middle school. We even experience it everyday, thanks to the industrialization, urbanization and globalization. Plants and their importance is also well known to us. We are alive because of these producers in our food web. But, plants are taken for granted by humans as many other natural resources. And that’s the reason why we see natural calamities very often these days.
Effects of Air Pollution on Plants:
Now, coming on to the topic, effects of air pollution on plants. The gaseous effluents emitted from the vehicles and chimneys comprise of noxious gases such as sulfur dioxide, carbon monoxide, nitrogen oxides, ground level ozone, etc. The dust particles, soot, etc are collectively known as particulate matter are also deleterious to the environment. Both gaseous effluents and particulate matter damage the plants. Let’s understand this in detail today.
Reduction in Photosynthesis: Scientists report that due to reduction in leaf area, as an adaptive measure to air pollutants, the overall rate of photosynthesis reduces. This is reported in trees such as Mango tree (Mangifera indica), Neem tree (Azadirachta indica), etc. Increased concentrations of gaseous pollutants might lead to reduction in the photosynthetic efficiency of the leaves leading to reduced growth and productivity in plants.
Reduction in Plant Growth: In case of trees, this reduction refers to reduction in height of the plant, tree canopy, etc. Due to decrease in the photosynthetic activity of the plants, less food is prepared by the plant that leads to the reduction in the overall growth of the plant. Scientists also report that due to exposure to toxic dust particle, plants shed their leaves that result in the stunted growth of the plants.
Morphological Changes: The decrease in the leaf area, leaf length and leaf breadth correspond to the morphological changes in the plants. Some plants may have necrotic lesions, chlorosis, etc due to air pollution. These are also sometimes referred as morphological changes. The morphological changes are the result of the physiological and biochemical changes in the plants.
Micro-morphological Changes: These changes are related to the stomata, epidermal cells and other related cells present in the leaves of a plant. Scientific studies reveal that changes take place in the size of stomata, size of epidermal cells, number of stomata, length and breadth of the epidermal cells due to air pollution. The size of stomata and the stomatal frequency decreases in the leaves of the plants growing in a polluted area when compared with a plant growing in a less polluted are or residential area.
Biochemical Changes: Reduction in photosynthesis is related to the reduction in chlorophyll concentration. Chlorophyll pigment is responsible for the food production in the plants. Scientists believe that as the chlorophyll content of plants reduce due to increased air pollutants, the rate of photosynthesis drastically decreases in the leaves. Some plants have also shown opposite results. Concentration of total soluble sugars and starch are also found to decrease significantly in the trees from the polluted regions. Not only these, the total protein content is also reduced in the trees exposed to polluted air.
Do All Plants Behave Similarly to Air Pollutants?
No, not all plants behave similarly to environmental changes. Some plants try to adapt themselves to the changing environment. Scientists report adaptation in plants to air pollutants. When plants are exposed to air pollutants for example, plants growing along the roadside or in the industrial belt, the plants adapt themselves to even sustain in adverse environmental conditions. The adaptive measures that can be seen in plants due to air pollutants are:
Reduced leaf structure: The plants might reduce their leaf structure in order to reduce the exposure of the pant to the air pollutants. Since, the leaf area gets reduced, the number of stomata (openings on the leaves) also lessen and less noxious gases enter the plant.
Increased Photosynthetic Activity: Not all plants show reduction in chlorophyll content due to air pollutants. Few plants have shown increased photosynthesis due to high availability of chlorophyll content as an effect of air pollution.
Alteration in Stomata: Some scientists have reported that plants can also alter the shape of stomata and the nearby cells to reduce interaction with the outer world.
Such plants that can tolerate poisonous gases and particulate matters are considered tolerant species. Scientists suggests that more and more such plants should be grown near the industries, factories and along the roadside to reduce air pollution.
The urban air pollution is affecting crops, plants, and trees significantly. Air pollution is causing both acute and chronic damage to morphological, anatomical and physiological characteristics of the leaves of plants growing in the polluted area. Measures should be taken to reduce air pollution. One of the most effective way to combat air pollution can be reforestation.